Expression of Fas and Fas ligand mRNA in rat and human preimplantation embryos

Cyt-C Mediated Mitochondrial Pathway Plays an Important Role in Oocyte Apoptosis in Ricefield Eel (Monopterus albus)

Apoptosis plays a key role in the effective removal of excessive and defective germ cells, which is essential for sequential hermaphroditism and sex change in vertebrates. The ricefield eel, Monopterus albus is a protogynous hermaphroditic fish that undergoes a sequential sex change from female to male. Previous studies have demonstrated that apoptosis is involved in sex change in M. albus. However, the apoptotic signaling pathway is unclear. In the current study, we explored the underlying mechanism of apoptosis during gonadal development and focused on the role of the mitochondrial apoptosis signaling pathway in sex change in M. albus. Flow cytometry was performed to detect apoptosis in gonads at five sexual stages and ovary tissues exposed to hydrogen peroxide (H2O2) in vitro. Then the expression patterns of key genes and proteins in the mitochondrial pathway, death receptor pathway and endoplasmic reticulum (ER) pathway were examined. The results showed that the apoptosis rate was significantly increased in the early intersexual stage and then decreased with the natural sex change from female to male. Quantitative real-time PCR revealed that bax, tnfr1, and calpain were mainly expressed in the five stages. ELISA demonstrated that the relative content of cytochrome-c (cyt-c) in the mitochondrial pathway was significantly higher than that of caspase8 and caspase12, with a peak in the early intersexual stage, while the levels of caspase8 and caspase12 peaked in the late intersexual stage. Interestingly, the Pearson’s coefficient between cyt-c and the apoptosis rate was 0.705, which suggests that these factors are closely related during the gonadal development of M. albus. Furthermore, the cyt-c signal was found to be increased in the intersexual stage by immunohistochemistry. After incubation with H2O2, the mRNA expression of mitochondrial pathway molecules such as bax, apaf-1, and caspase3 increased in ovary tissues. In conclusion, the present results suggest that the mitochondrial apoptotic pathway may play a more important role than the other apoptotic pathways in sex change in M. albus.

Prediction model for aneuploidy in early human embryo development revealed by single-cell analysis

Aneuploidies are prevalent in the human embryo and impair proper development, leading to cell cycle arrest. Recent advances in imaging and molecular and genetic analyses are postulated as promising strategies to unveil the mechanisms involved in aneuploidy generation. Here we combine time-lapse, complete chromosomal assessment and single-cell RT-qPCR to simultaneously obtain information from all cells that compose a human embryo until the approximately eight-cell stage (n=85). Our data indicate that the chromosomal status of aneuploid embryos (n=26), including those that are mosaic (n=3), correlates with significant differences in the duration of the first mitotic phase when compared with euploid embryos (n=28). Moreover, gene expression profiling suggests that a subset of genes is differentially expressed in aneuploid embryos during the first 30 h of development. Thus, we propose that the chromosomal fate of an embryo is likely determined as early as the pronuclear stage and may be predicted by a 12-gene transcriptomic signature.

Soluble ligands and their receptors in human embryo development and implantation

Extensive evidence suggests that soluble ligands and their receptors mediate human preimplantation embryo development and implantation. Progress in this complex area has been ongoing since the 1980s, with an ever-increasing list of candidates. This article specifically reviews evidence of soluble ligands and their receptors in the human preimplantation stage embryo and female reproductive tract. The focus will be on candidates produced by the human preimplantation embryo and those eliciting developmental responses in vitro, as well as endometrial factors related to implantation and receptivity. Pathways to clinical translation, including innovative diagnostics and other technologies, are also highlighted, drawing from this collective evidence toward facilitating joint improvements in embryo quality and endometrial receptivity. This strategy could not only benefit clinical outcomes in reproductive medicine but also provide broader insights into the peri-implantation period of human development to improve fetal and neonatal health.

Effects of cumulus cells on in vitro maturation of oocytes and development of cloned embryos in the pig

The purpose of this study was to investigate the role of porcine cumulus cells (CC) in oocyte maturation and somatic cell nuclear transfer (SCNT) embryo development in vitro. Denuded pig oocytes were co-cultured with CC or routinely cultured in maturation medium without a feeder layer. Porcine CC inactivated with mitomycin C or non-inactivated were used for the feeder layer in co-culture with porcine SCNT embryos to investigate comparatively the developmental competence of cloned embryos. The DNA damage aspects of apoptosis and expression pattern of genes implicated in apoptosis (Fas/FasL) as well as the mRNA expression of DNA methyltransferase (Dnmt1, Dnmt3a) of porcine SCNT embryos were also evaluated by comet assay or real-time RT-PCR, respectively. The results showed that co-culture with CC improved the extrusion rate of pbI (49.3% vs 31.5%, p<0.05) and survival rate (75.7% vs 53.3%, p<0.05) of denuded oocytes, but had no effects on blastocyst developmental rate or 2-cell-stage survival rate of in vitro fertilization embryos. Co-culture with CC inactivated by mitomycin C improved the blastocyst developmental rate (26.6% vs 13.0%, p<0.05) and decreased the apoptotic incidence (27.6% vs 46.2%, p<0.05) of porcine cloned embryos. Co-culture with inactivated CC reduced Fas and FasL mRNA expression of cloned embryos at the blastocyst stage compared with NT controls (p<0.05), but there were no differences in Dnmt1 and Dnmt3a mRNA expression among groups. Co-culture with inactivated cumulus cell monolayer significantly increased blastocyst formation and decreased the apoptotic incidence in porcine cloned embryos during in vitro development.

BAX pro-apoptotic gene alterations in repeated pregnancy loss

INTRODUCTION

Recurrent pregnancy loss (RPL) is a critical medical problem in about 0.5-2% of women. The molecular genetic background for spontaneous abortion is being increasingly understood, and some polymorphisms associated with it have been reported. This study investigates alterations of the Bax gene as a pro-apoptotic gene in women with idiopathic RPL.

MATERIAL AND METHODS

The frequency of mutations in the Bax gene of 67 idiopathic RPL women was studied in comparison to a sample of 70 healthy women. The promoter and the entire coding regions (exons 1-7) were amplified using polymerase chain reaction (PCR). The purity of the PCR product was first verified by electrophoresis on a 2% agarose gel. The amplified fragment was then sequenced by automated DNA sequencing.

RESULTS

A statistically significant difference was observed between patients and the control group regarding the frequency of alleles A(-179)G in the Bax promoter region (p= 0.013). Also among patients, G90C and G95A transitions were found in the coding region of exon 1 that change amino acid glutamine (Q) to histidine (H) and arginine (R) to lysine (K), respectively. A statistically significant association was observed between H allele (p = 0.0001) and K allele (p< 0.0001) and the occurrence of RPL.

CONCLUSIONS

Our results indicate an association between A(-179)G mutation in the Bax promoter and RPL. Moreover, two polymorphisms, G90C and G95A in exon 1, found among our patients, could be considered as genetic factors making people susceptible to miscarriages. According to our findings, the Bax gene has an important role in pregnancy loss and the variations of this gene could help in the assessment of RPL.

Protective potential of SCF for mice preimplantation embryos cultured in vitro in suboptimal conditions

PURPOSE

To examine the effect of stem cell factor (SCF) to embryos exposed to detrimental factors.

METHODS

Mice embryos cultured in control medium or Exp.1. with FasL or FasL+SCF Exp.2. with hydrogen peroxide (HP) or HP+SCF; Exp.3. frozen-thawed and cultured with or without SCF. Immunohistochemistry for Fas and c-kit receptors was performed in blastocysts. Blastocyst rates, total numbers of blastocyst cells (TB) and inner cell mass cell counts (ICM) were determined.

RESULTS

Immunohistochemical studies revealed expression of both Fas and c-kit in blastocyst cells. Exp.1. Significantly more blastocysts were found in control when compared to FasL group and to FasL+SCF group. TB and ICM counts in control and FasL+SCF group were significantly higher comparing to FasL group. Exp.2. We found significant differences between three groups in all three evaluated parameters. The highest blastocyst rates, TB and ICM counts were found in control, lower in HP+SCF group and the worst in HP group. Exp.3. No significant differences in TB and ICM counts were found. More embryos formed blastocyst in control than in two cryopreserved groups. Blastocyst rates did not differ between two cryopreserved groups.

CONCLUSION

SCF may improve culture of embryos exposed to unfavorable milieu.

Coelomic cells show apoptosis via Fas/FasL system: a comparative study between healthy human pregnancies and missed miscarriages

BACKGROUND

The Fas/Fas ligand (FasL) system represents one of the main apoptotic pathways controlling placental apoptosis throughout gestation. In the current study, we have examined the Fas/FasL protein expression and the apoptotic incidents of coelomic cells, amniotic cells and trophoblastic tissue in first trimester human pregnancies and missed miscarriages (MM).

METHODS

Protein expression was determined by immunofluoresence, western blotting analysis, immunohistochemistry and indirectly by RT-PCR, whereas apoptotic cell death was assessed by in situ DNA fragmentation analysis.

RESULTS

Coelomic cells express Fas/FasL proteins, can undergo apoptosis and were the only cells in which apoptosis, Fas protein expression and FasL protein expression were accordingly increased along with gestational age (P = 0.001, P = 0.008; P = 0.012, respectively). In contrast, amniotic cells and trophoblast showed a consistency in the expression levels of Fas/FasL proteins in healthy pregnancies. MM were accompanied by increased Fas/FasL protein expression in all examined samples (P < 0.001). The increase of Fas/FasL protein expression was accompanied by proportional increase of apoptotic incidents among the coelomic cell population (P = 0.023, P = 0.009, respectively), whereas amniotic cells and trophoblast appeared to be resistant to Fas-induced apoptosis. The lowest expression of Fas/FasL proteins and the minimum occurrence of apoptotic incidents were detected in the trophoblast.

CONCLUSIONS

These data suggest that there is a different regulation and function of the Fas/FasL system in early human pregnancies. Aberration of the Fas-mediated apoptosis may represent one of the execution-step necessary for pregnancy loss in MM cases.

Increase in DNA fragmentation and apoptosis-related gene expression in frozen-thawed bovine blastocysts

Evaluation of apoptosis and expression level of apoptosis-related genes is useful for examining the variation in embryo quality according to environmental change. The objective of this study was to investigate DNA fragmentation and apoptosis-related gene expression patterns in frozen-thawed bovine blastocysts.In vitroproduced day 7 blastocysts were frozen by two different vitrification methods (conventional 0.25 ml straw or MVC straw). After thawing, DNA fragmentation of surviving embryos was examined by TUNEL assay, and the expression patterns of their apoptotic genes (survivin, Fas, Hsp 70 and caspase-3) were evaluated using real-time quantitative reverse transcriptase polymerase chain reaction.In vitrosurvival rates of frozen-thawed embryos were higher following the MVC vitrification method (88.2% re-expanded at 24 h, 77.1% hatching at 48 h) than the conventional (C) vitrification method (77.0% re-expanded at 24 h, 66.7% hatching at 48 h). However, both vitrified methods resulted in a significantly higher apoptotic index (C vitrification method 11.9%, MVC vitrification method 11.0%) than in non-frozen embryos (3.0%). Expression levels of survivin, Fas, caspase-3, and Hsp 70 were also increased in the frozen-thawed embryos compared with non-frozen embryos. These results indicate that the cryopreservation procedure might cause damage that results in an increase in DNA fragmentation and apoptosis-related gene transcription, reducing developmental capacity of frozen-thawed embryos.

Regulation of proliferation and apoptosis during development of the preimplantation embryo and the placenta

The preimplantation embryo starts as a single cell, the zygote. The first cell divisions do not lead to volume expansion, but rather to an increasing number of small cells. At the morula stage the first two cell lineages differentiate into the trophoblast and the inner cells mass/embryoblast. During development of the preimplantation embryo, apoptosis occurs only after the onset of the embryonic genome. It has become clear that the development of a healthy child requires not only very high rates of proliferation and differentiation, but also apoptosis, which is a crucial mechanism for morphogenesis and the development of the inner organs. Furthermore, the generation of specific cell types, such as lens cells, erythrocytes, and thrombocytes, depends on the apoptosis pathways. This is also true later in gestation, when the trophoblasts form the placenta and provide the epithelial cover of the villous trees of the placenta. This layer is in direct contact with maternal blood and, as do all epithelia, displays a continuous turnover of cells. Thus, apoptosis is a normal constituent of survival in this layer as well, and changes in the regulation and rate of apoptosis have deleterious effects on the trophoblast and consequently the developing embryo or fetus. Here we present a very brief overview of the importance of apoptosis for the development of the preimplantation embryo and the maintenance of placental trophoblasts. Furthermore, we highlight what happens when regulation of proliferation or apoptosis fails in these systems, and attempt to show that apoptosis is only the consequence of poor embryo or trophoblast development -- not its cause.

Insulin-like growth factor-I alters apoptosis related genes and reduces apoptosis in porcine parthenotes developing in vitro

The aim of this study was to determine the effects of IGF-I on the viability and development of porcine presumptive diploid parthenotes developing in vitro. In vitro derived 2-cell parthenotes were cultured to blastocysts with or without exogenous IGF-I in the presence or absence of BSA. The addition of 10 or 100 ng/ml IGF-I into NCSU 23 medium did not enhance the development of 2-cell parthenotes to the blastocyst stage. However, IGF-I increased cell numbers (P < 0.001) in the presence of BSA. Similarly, IGF-I alone did not affect apoptosis in the blastocysts but when combined with BSA, it reduced apoptosis (P < 0.05). Real time reverse-transcription polymerase chain reaction revealed that IGF-I significantly decreased the mRNA expression (pro-apoptotic gene Fas or Bak and anti-apoptotic gene Bcl-xL) ratios of both Fas/Bcl-xL (P < 0.01) and Bak/Bcl-xL (P < 0.01) in the presence of 0.4% BSA. These data suggest that IGF-I synergies with BSA to act as a mitogen and apoptotic survival factor in porcine preimplantation parthenotes.

Polyamines inhibit apoptosis in porcine parthenotes developing in vitro

Polyamines, namely putrescine, spermidine, and spermine, are biogenic low-molecular-weight aliphatic amines which play essential roles in cell growth and proliferation. The aim of this study was to determine the effects of polyamines on the viability and development of porcine diploid parthenotes developing in vitro. The addition of 0.1 or 1.0 microM of putrescine, spermidine, or spermine, individually, to the culture medium did not enhance the development of 2-cell parthenotes to the blastocyst stage and did not change the total number of nuclei in the blastocysts. However, combined addition of these three compounds increased developmental rate to blastocyst and total cell numbers. Apoptosis in blastocyst stage parthenotes was decreased in the presence of exogenous polyamines. Real time PCR revealed that addition of polyamines to the culture media decreased the ratio of mRNA expression of Bak/Bcl-xL, Fas/Bcl-xL, and caspase 3, and enhanced mRNA expression of ornithine decarboxylase (ODC) and spermidine synthase, enzymes of polyamine biosynthesis. In the presence of L-alpha-difluoromethyl ornithine (an inhibitor of ODC) or cyclohexylamine (an inhibitor of spermidine synthase) development of porcine parthenotes decreased, apoptosis increased, and mRNA expression of the ratio of Bak/Bcl-xL and Fas/Bcl-xL, and caspase 3 increased. These results suggest that exogenous polyamines in the culture medium prevent apoptosis of porcine parthenotes and results in the net enhancement of porcine embryo viability.

Deadly decisions: the role of genes regulating programmed cell death in human preimplantation embryo development

Human preimplantation embryo development is prone to high rates of early embryo wastage, particularly under current in vitro culture conditions. There are many possible underlying causes for embryo demise, including DNA damage, poor embryo metabolism and the effect of suboptimal culture media, all of which could result in an imbalance in gene expression and the failed execution of basic embryonic decisions. In view of the complex interactions involved in embryo development, a thorough understanding of these parameters is essential to improving embryo quality. An increasing body of evidence indicates that cell fate (i.e. survival/differentiation or death) is determined by the outcome of specific intracellular interactions between pro- and anti-apoptotic proteins, many of which are expressed during oocyte and preimplantation embryo development. The recent availability of mutant mice lacking expression of various genes involved in the regulation of cell survival has enabled rapid progress towards identifying those molecules that are functionally important for normal oocyte and preimplantation embryo development. In this review we will discuss the current understanding of the regulation of cell death gene expression during preimplantation embryo development, with a focus on human embryology and a discussion of animal models where appropriate.

TRAIL and KILLER Are Expressed and Induce Apoptosis in the Murine Preimplantation Embryo1

TRAIL (tumor necrosis factor [TNF]-related apoptosis-inducing ligand) and KILLER are a death-inducing ligand and receptor pair that belong to the TNF and TNF-receptor superfamilies, respectively. To date, only one apoptosis-inducing TRAIL receptor (murine KILLER [MK]) has been identified in mice, and it is a homologue of human Death Receptor 5. Whereas the expression of other death receptors, such as Fas and TNF receptor 1 have been documented in mammalian preimplantation embryos, no evidence currently demonstrates either the presence or the function of TRAIL and its corresponding death receptor, MK. Using reverse transcription-polymerase chain reaction and confocal immunofluorescent microscopy, we found that both TRAIL and MK are expressed from the 1-cell through the blastocyst stage of murine preimplantation embryo development. These proteins are localized mainly at the cell surface from the 1-cell through the morula stage. At the blastocyst stage, both TRAIL and MK exhibit an apical staining pattern in the trophectoderm cells. Finally, using the TUNEL assay, we demonstrated that MK induces apoptosis in blastocysts sensitized to TRAIL via actinomycin D. Taken together, these data are the first to demonstrate the presence and function of TRAIL and MK, a death-inducing ligand and its receptor, in mammalian preimplantation embryos.

Apoptosis in sea breamSparus aurata eggs

In the present study, the sea-bream Sparus aurata, a pelagic egg spawner, was used as experimental model, in order to establish the occurrence of apoptosis in vertebrates with external reproduction. The same female ovulates floating and nonfloating eggs, but only the former, after fertilization, proceed to embryo development. The eggs were divided into floating and nonfloating and both were analyzed for the presence of several apoptosis markers. The results here reported provide evidence that the nonfloating cells present severe shrinkage and highly express both FAS receptor and FAS ligand on their surface. Furthermore, DNA fragmentation and mitochondria swelling were found, suggesting that the nonfloating eggs were cells programmed to die.

Ghrelin inhibits the development of mouse preimplantation embryos in vitro

Although ghrelin acts as a modulator of feeding behavior and energy metabolism in the central nervous system, recent studies have implicated the peripheral actions of ghrelin in reproductive tissues. Here, we investigated the expression of ghrelin and its receptor (GHS-R) in mouse oocyte and preimplantation embryos, and we examined the role of ghrelin in the regulation of early embryo development. Both ghrelin and GHS-R mRNAs were detected in morula or more advanced embryo stages. As for the origin of ghrelin, both ghrelin mRNA and protein were identified in the uterine endometrium. The levels of ghrelin in uterine fluid as well as plasma were significantly increased in fasting mice compared with animals with free access to foods. Addition of ghrelin to culture media inhibited the development of two-cell embryos to the hatched blastocysts, and the inhibitory effects of ghrelin were abolished by an antagonist for the GHS-R. In addition, ghrelin significantly decreased the number of total cells, inner cell mass, and trophectoderm cells in blastocysts. These observations suggest that ghrelin could inhibit the development of preimplantation embryos during fasting. Thus, ghrelin may act as a peripheral factor to avoid the excess metabolic demands imposed by pregnancy during malnutritional states.

The role of leptin during the development of mouse preimplantation embryos

Leptin is known to regulate diverse reproductive functions, and recent studies have implicated involvement of leptin in the early mouse embryo development. The aim of the present study was to investigate the expression of leptin and its functional receptor (OB-Rb) in mouse oocyte and preimplantation embryo, and to examine whether leptin influenced the early embryo development. Leptin mRNA was detected in blastocyst and hatched blastocyst, and OB-Rb mRNA was detected in oocytes, 1-cell, 2-cell, morula, blastocyst and hatched blastocyst. As for the origin of leptin, leptin mRNA was identified in both the oviduct and uterus of the pregnant mouse. Furthermore, in the pregnant mouse, the levels of leptin in uterine fluid were higher than those in the non-pregnant mouse. Supplementation of culture medium with leptin promotes the development of preimplantation embryos from 2-cell stage to the blastocysts, fully expanded blastocysts and hatched blastocysts. Leptin significantly increased the total cell number of blastocysts, and the effect was preferentially observed in the trophectoderm. These findings raise the possibility that leptin regulates the development of mouse preimplantation embryo through a paracrine pathway.

Expression of LDL receptor and uptake of LDL in mouse preimplantation embryos

OBJECTIVES

The aim of this study is to address the role of low-density lipoprotein (LDL) on mouse preimplantation embryos.

METHODS

The temporal expression of low-density lipoprotein receptor (LDLR) and side-chain cleavage cytochrome P450 (P450scc) mRNAs in mouse oocytes and preimplantation embryos up to the hatched blastocyst stage were analyzed by RT-PCR and nested PCR techniques. Simultaneously, the expression of LDLR in the protein level was analyzed by fluorescent immunohistochemistory at oocyte, 4-cell embryo and blastocyst. Uptake of LDL was analyzed using the LDL labeled with the fluorescent probe DiO.

RESULTS

LDLR mRNA was detected at oocyte, 8-cell, morula, blastocyst and hatched blastocyst stages. P450scc mRNA was detected at oocyte, 1-cell, 2-cell, 4-cell, blastocyst and hatched blastocyst stages. LDLR protein was detected in blastocyst. P450scc protein was detected in oocyte, 4-cell, and blastocyst. LDL-DiO was taken into embryo at blastocyst stage and this uptake was competitively suppressed by excess unlabeled LDL.

CONCLUSIONS

It is suggested from the present study that LDLR may play an essential role in uptake of exogenous LDL into blastocyst stage and cholesterol derived from LDL may be the source of steroid hormone synthesis.

Survivin acts as an antiapoptotic factor during the development of mouse preimplantation embryos

Apoptosis is an essential physiologic process used in almost all tissues to remove damaged or superfluous cells. However, the early embryos are unique because no cell death is found up to the blastocyst stage during normal development. Survivin, a member of the IAP family, is capable of binding to caspases to modulate their functions. Here, we investigated the expression of survivin, and its role in preventing apoptosis in mouse preimplantation embryos. Transcripts for survivin and a splice variant lacking exon 2 were detected from unfertilized oocytes up to hatched blastocyst stage. At the protein level, survivin was also detected at all stages of early embryos. The antisense approach was used to demonstrate the role of survivin on embryo development. Development of early embryos treated with antisense survivin oligonucleotides was arrested at the morula or early blastocyst stage with disruption of tubulin formation and abnormal nuclei, associated with apoptosis. The effect of the antisense was enhanced by cotreatment with an apoptosis-inducing reagent, staurosporine. In contrast, apoptosis induced by the antisense treatment was inhibited by caspase-3 and -9 inhibitors. These results indicate that survivin is an essential antiapoptotic gene expressed in preimplantation embryos and could protect the embryos from apoptosis by inhibiting an apoptotic pathway involving caspases.

Leptin promotes the development of mouse preimplantation embryos in vitro

Leptin acts as a modulator of diverse reproductive functions, and recent studies have implicated involvement of leptin in the early embryo development in mammal. The aim of this study was to investigate the expression of leptin and its receptor (OB-R) in mouse oocyte and preimplantation embryo, and to examine whether leptin influenced the early embryo development. Leptin mRNA was detected in blastocyst and hatched blastocyst, and two splice variants of OB-R (OB-Ra and OB-Rb) mRNAs were detected in oocytes, 1-cell, 2-cell, morula, blastocyst, and hatched blastocyst. As for the origin of leptin, both leptin mRNA and protein were identified in the oviduct epithelium and endometrium of pregnant mouse. In the pregnant mouse, the levels of leptin in uterine fluid were higher than those in nonpregnant mouse. Addition of leptin to embryo culture media promotes the development from 2-cell stage embryos to the blastocysts, fully expanded blastocysts and hatched blastocysts. This effect was neutralized by an antibody against the extracellular domain of OB-R. Leptin significantly increased the total cell number of blastocysts, and the effect was preferentially observed in the trophectoderm. These findings raise the possibility of a paracrine/autocrine leptin signaling system regulating the development of mouse preimplantation embryo.